1. Field of the Invention
The present invention relates to a solid-state image sensor.
2. Description of the Related Art
A technique of improving the focusing property of light by forming a lightguide in a region on a photoelectric conversion portion such as a photodiode which constitutes a pixel is known. Japanese Patent Laid-Open No. 2004-221532, for example, discloses a structure in which the width of a lightguide, that is, a light-guiding portion decreases from the light incident side to the light reception side (the side on which a photoelectric conversion portion is formed). According to Japanese Patent Laid-Open No. 2004-221532, this structure receives a large amount of incident light to improve the focusing property.
Also, Japanese Patent Laid-Open No. 2008-85174 discloses a structure which uses a lightguide having a light-guiding portion with a vertical side surface on the light incident side, and an inclined side surface near the light reception side (light wavelength range). According to Japanese Patent Laid-Open No. 2008-85174, this structure prevents evanescent light generated upon total reflection from leaking out of the light-guiding portion.